R^2NC: Redundant and Random Network Coding for H.264/SVC Transmission

Network coding (NC) and erasure coding (EC) share a common principle of encoding incoming data packets at network intermediate nodes so that destination nodes can reconstruct the original data packets using a sufficient number of encoded data packets collected at the destinations. While NC in general reduces the number of packets sent through the network, EC introduces redundancy into the packet streams to recover from lost packets. Many research papers in NC assume loss-free packet transmission, and to address this issue, end-to-end packet loss recovery through EC has been proposed. In this paper, we investigate hop-by-hop packet loss recovery through EC so as to avoid the accumulation of lost packets throughout the network using flow oriented EC. Specifically, we explore combined NC and EC at intermediate nodes in the networks to allow for improved packet loss recovery compared to end-to-end EC. Different implementations trading the packet processing complexity at the intermediate and destination nodes are considered. This paper first examines the effects of data loss in NC and then the improvements achievable with the proposed method are presented.

We propose an efficient Adaptive Random Convolutional Network Coding (ARCNC)\nalgorithm to address the issue of field size in random network coding. ARCNC\noperates as a convolutional code, with the coefficients of local encoding\nkernels chosen randomly over a small finite field. The lengths of local\nencoding kernels increase with time until the global encoding kernel matrices\nat related sink nodes all have full rank. Instead of estimating the necessary\nfield size a priori, ARCNC operates in a small finite field. It adapts to\nunknown network topologies without prior knowledge, by locally incrementing the\ndimensionality of the convolutional code. Because convolutional codes of\ndifferent constraint lengths can coexist in different portions of the network,\nreductions in decoding delay and memory overheads can be achieved with ARCNC.\nWe show through analysis that this method performs no worse than random linear\nnetwork codes in general networks, and can provide significant gains in terms\nof average decoding delay in combination networks.\n

The IEEE 802.16 standard, or WiMAX, has emerged to facilitate high-bandwidth wireless access in real- world metropolitan areas, commonly referred to as 4G. In WiMAX, hybrid automatic repeat request (HARQ) is adopted to transmit data packets reliably. However, it sacrifices resilience in time varying channels, and it may under-utilize the wireless medium in the cases of multi-path and multi-hop transmissions. On the other hand, random network coding has been shown to be effective towards improving throughput in multi-hop wireless networks, when deployed above the physical and MAC layers. It would be encouraging to observe that network coding is also helpful at the MAC layer in practice, especially within the emerging WiMAX standard. Is random network coding beneficial in WiMAX at the MAC layer? We seek to answer this question by evaluating network coding in three cases: single-hop transmissions, handovers, and multi-hop transmissions. We show that random network coding has indeed offered important advantages as compared to traditional HARQ. Our observations may lead to the use of random network coding at the MAC layer in practical WiMAX systems.

With Network Coding, a source can multicast information at a rate approaching the smallest minimum cut between the source and any terminal through encoding the incoming packets at intermediate node. On the other hand, in current wireless systems, terminals could receive multiple cells signal, but only registered cell's packets could be used, and others are dropped as useless or noise. This traditional way didn't make full use of information received by terminals. In this paper, a new transmission scheme using random network coding (RNCT) is introduced, in which all signals received by terminal are useful. Simulations show that this new scheme can improve spectral efficiency and wireless system throughput significantly than current transmission scheme (CTS).

Network coding-based approach for efficient video streaming over MANET

It has been shown in the literature that Network Coding (NC) can boost the performance of wireless networks. However, to really obtain the potential gain of NC, efficient Medium Access Control (MAC) protocols that operate with awareness of the NC functions are necessary. In this paper, we propose a novel NC-aware MAC protocol for IEEE 802.11 wireless networks that combines k-batch transmissions and multiple receiver-initiated reverse direction exchanges involving NC data to boost the overall network performance. The proposed protocol allows any node to transmit a burst of data packets in a single channel access invocation. Then, an intermediate node can transmit an NC data packet when receiving a valid data packet from a source node, without contending for channel access. Both analytical and simulation results presented in this paper show the high throughput and energy efficiency of the proposed protocol with gains ranging from 33% to 298% when compared to existing mechanisms based on the IEEE 802.11 Standard.∗

In this work, routing and spectrum allocation (RSA) algorithms together with network coding (NC) are proposed for elastic optical networks. NC has been used in optical networks for protection against link failures and also in multicasting to improve spectral efficiency. In this work, NC is used to protect confidential connections against eavesdropping attacks. The confidential signals are XOR-ed with other signals at different nodes in their path while transmitted through the network. These signals can be combined either at the source node and/or at intermediate nodes. To implement NC for confidential connections, a set of constraints for the NC problem in addition to the constraints of the RSA problem are incorporated to the algorithms. The combination of signals through network coding significantly increases the security of confidential connections, since an eavesdropper will receive a combination of signals from different connections, making it extremely difficult for the confidential signal to be decrypted. A number of RSA strategies are examined in terms of confidentiality, spectrum utilization, and blocking probability. Performance results demonstrate that network coding provides an additional layer of security for confidential connections with only a small increase in the spectrum usage.

Connectivity, losses, and buffering are factors that directly affect the performance of network coding. These factors affect the ability of intermediate nodes to generate useful encodings; these are encodings that contribute in propagating and recovering data at receiver node(s). It has been shown that in particular scenarios network coding performance can be improved by simply increasing the generation size (k); however, this leads to increasing transmission overhead, encoding complexity and (more importantly) buffer sizes at intermediate nodes. In this paper, we propose a new network coding approach where we employ Multi-Generation Mixing (MGM). MGM eliminates the need to increasing buffer sizes while improving the performance of network coding. Under MGM, we define a mixing set of size m generations that can be network coded (mixed) together. Within each MGM mixing set, a new set of generation packets are mixed with previously transmitted (network coded) generations. This generalized approach provides a great deal of resilience against losses when compared with traditional generation-based network coding. Our analysis of the performance of MGM-based network coding demonstrates significant reduction in required overhead for a given recovery performance at the receivers. We also illustrate the performance of MGM using extensive simulations that provide a useful insight into the viability of MGM-based network coding.

Emergency communications require reliability and flexibility for disaster recovery and relief operation. Based upon existing commercial portable devices (e.g., smartphones, tablets, laptops), we propose a network architecture that uses cellular networks and WiFi connections to deliver large files (e.g. detailed maps) in emergency scenarios under the impairments of wireless channel such as packet losses and intermittent connection. Network coding (NC) is exploited to improve the delivery probability beyond cellular coverage. We first review the state-of-the-art of NC for emergency communications. Then, we present the proposed network architecture which utilizes multiple radio interfaces of portable devices to support data delivery. A random linear NC scheme is exploited both at the source and intermediate nodes, and an analytical model for the successful decoding probability is derived. Finally, we evaluate the effectiveness of the proposed architecture with NC in terms of the delivery ratio of content for intermittent connectivity scenarios.

In a classical network, data streams originating from a source and intended to a desired destination are routed through intermediate nodes before reaching their final destination. By contrast, Network Coding (NC) manipulates at an intermediate node those data streams by combining the data from the streams before forwarding it to the destination. This paper describes the advances of NC in wireless communication for IMT-Advanced and beyond. A short overview of NC in wireless communications is given first. Afterward, the application of NC to broadcasting is described. Thereafter, NC methods in uplink wireless communications, such as User Grouping (UG) and Relay Selection (RS) are described. Further, the advantage of non-binary over binary network NC is shown in a multi-user multi-relay scenario. Finally the performance of NC is analyzed. In particular, in the uplink Multiple Access Relay Channel (MARC) scenario, the joint UG and RS methods lift the system capacity by 70%. The non-binary NC improves the SNR up to 4 dB. Finally the efficient broadcast method yields up to 22% overhead reduction compared to ARQ.

Chapter 1 - An Introduction to Network Coding

Network coding is a promising technology to improve throughput and reliability. However, the benefit of network coding is restricted and affected by network topology, especially in peer-to-peer system. Precise topology awareness can be helpful to improve system performance of network coding in terms of throughput and reliability. In this paper, we propose an innovative scheme TANCF (Topology Awareness based on Network Coding with Feedback), to detect the path in hierarchical P2P network based on the feedback from the intermediate nodes and the receiver nodes of network coding system. It is a first attempt to use network coding with feedback to reveal the network connectivity and to construct the network topology. In the TANCF scheme, the path matrix of network can be obtained by the feedback from intermediate nodes and receiver nodes, which has a close relationship with the adjacency matrix of topology, so that it can be used to construct the network topology that lead to optimize the parameters of network coding. Through the matrix analysis and simulation experiment, it can be proved that TANCF scheme can obtain the path matrix correctly with a high probability.

In this letter, we consider a wireless network where the transmitter, such as a base station, multicasts hard-deadline-constrained prioritized data to users over fading channels. We propose a new cross-layer transmission scheme that involves simultaneous smart antenna beamforming at physical layer and random network coding at network layer to maximize the overall network throughput. In this joint design, beamforming is used for dynamic transmitting power allocation to achieve power gain; while the random network coding is adopted to achieve coding gain. The simulation results show the effectiveness of the proposed algorithm.

We study joint network-coding and channel-coding design to optimize delay performance. In our systems, network codes (network layer) are on top of channel codes (physical layer). Network codes run in a rateless random method, i.e., source and intermediate nodes randomly produce and transmit codewords until transmission succeeds. Thus, the rateless network codes have block-erasure-correction capability. The physical layer codewords are disturbed by channel noise. For the constraint of finite transmission time (finite block length), transmission errors are inevitable in the physical layer. We show that the physical-layer erasure probability is affected by both layers. Then, there is an interaction between network codes and channel codes, concerning the delay measure of the networks. We model the delay of each generation as the independent, identically distributed random variables. We show tradeoffs between the network layer and the physical layer on the length of network codewords, and on the transmission time of physical-layer codewords. To measure delay performance, we use expected delay and network-layer decoding error probability of a given delay, which are measures for networks without and with strict maximum-delay constraints, respectively. We show how to evaluate these measures for the coded networks with erasure channels. Then, we formulate problems to optimize the delay performance, and solutions are suggested.

With more and more multimedia applications on the Internet, such as IPTV, bandwidth becomes a vital bottleneck for the booming of large scale Internet based multimedia applications. Network coding is recently proposed to take advantage to use network bandwidth efficiently. In this paper, we focus on massive multimedia data, e.g. IPTV programs, transportation in peer-to-peer networks with network coding. By through study of networking coding, we pointed out that the prerequisites of bandwidth saving of network coding are: I) one information source with a number of concurrent receivers, or 2) information pieces cached at intermediate nodes. We further proof that network coding can not gain bandwidth saving at immediate connections to a receiver end; As a result, we propose a novel model for IPTV data transportation in unstructured peer-to-peer networks with network coding. Our preliminary simulations show that the proposed architecture works very well.